The Tulsa Police Department said Officer Betty Shelby fired her weapon, killing Terence Crutcher, 40, who was unarmed. Danny Williams, U.S. Attorney of the Northern District of Oklahoma, said authorities are looking into a possible federal civil rights violation.

A police video shows Crutcher standing outside his vehicle on Friday with his hands in the air. Police officers follow him as he walks toward his SUV. Gunshots are fired, and Crutcher falls to the ground.

Crutcher’s family said his vehicle had broken down on the road, where he was waiting for help.

Shelby’s attorney claims she fired her gun because Crutcher appeared to reach for a weapon inside the vehicle. But the family’s legal team presented video evidence that shows the vehicle’s window was rolled up.

Tulsa police reported on Tuesday that the drug PCP was discovered in Crutcher’s vehicle.

Tulsa Police Chief Chuck Jordan asked the Justice Department to assist its investigation, Fox News reported. State and local authorities are also conducting their own investigations.